34-1: Latham : Stimulation of Sterigmatocvstis 



ready to harvest in seven to ten days when grown on solution A, 

 or in four to five days when asparagine replaced the NH^N03 ; 

 while the period of cultivation extended over two to three weeks 

 if the temperature fell to 2o''-2 5^ C. The lack of constant condi- 

 tions is to be regretted, especially in view of indications which may 



be discussed later 



The first effect of CHCi^ used in such an amount as is necessary 

 to cause noticeable stimulation is to retard the germination of the 

 spores. With the smallest quantities employed, the first hyphae 

 did not appear until six to twenty-four hours after growth had 

 started in the chloroform-free air. The second effect seen is the 

 production of toughened, buckled felts by a rapid growth accom- 

 panied by repression of conidial fructification, as observed also 

 when the organism is stimulated by salts, etc. At harvesting, 

 felts grown under optimum stimulation gave on an average crops 



m 



200 per cent, to 300 per cent, as heavy as the normal, rising in some 

 instances to 500 per cent, and 700 per cent. The curve repre- 

 senting the influence of CHCI3 on growth is similar to those of 

 other stimulants ; it rises in a characteristic manner to a maximum 

 and then falls again. 



Sterigmatocystis cultivated on solution A at a temperature 

 varying between 20° and 30° C. grows more luxuriantly when 

 the content of the atmosphere is, per liter, the vapor of |- c.c. of 

 liquid CHCij and the beneficial effect increases until \~^^ c.c. per 

 liter are used, when decrease begins. If the bell-jar contains per 

 liter over i c.c. of CHCI3 (vaporized), germination is permanently 

 stopped, although the spores will grow readily if placed in air. 

 When asparagine, instead of NH^NOj, is the source of nitrogen 

 (solution C) the sensitivity of the Sterigmatocystis is increased. 

 Optimum growth then takes place when \-\ c.c. of CHCI3 is 

 present per liter, and | c.c. is sufficient to arrest development. 



The augmentation in weight is accompanied by a relatively 

 lessened acid formation and sugar consumption ; that is to say, 

 the ratio of the acid to the crop, and of the sugar used to the crop 

 is lowered. For example, in Series X, Table I, the acid coefficient 

 is lowered from 2.3186 to .4160 grams per gram fungus when the 

 atmosphere held i c.c. of CHCI^ vaporized and to .3551 grams 

 per gram fungus when the content was X c.c. ; at the same time, 



